1. Field of the Invention
The present invention relates to splicing of optical fibers and more specifically to the splicing of at least three optical fiber ends by the use of a unique splicer block which is developed from memory polymers. Thus, the present invention is directed to splicers into which ends of optical fibers may be inserted and subsequently spliced in place into a plurality of cavities for permanent fiber optics transmission, and to methods of making the splicer as well as methods of using it.
2. Prior Art Statement
Hundreds of patents have issued which are directed to the art of fiber optics splicing and connecting. Most involve very complex mechanical connections and/or the use of optical adhesives or glues. Typical of the patents which show unique methods of splicing are the following:
U.S. Pat. No. 3,944,328 shows the simplistic approach of inline, butt-to-butt splicing of fiber optics utilizing a resinous block with aligned bores with mechanical retention inserts.
U.S. Pat. No. 4,178,067 involves the use of a mass of dimensionally unstable material in cylindrical form which is radially shrunk. After the fiber optics are inserted butt-to-butt, upon causing the unstable matter to expand radially, the presence of the outer sleeve forces the unstable matter to compress and cause co-linear alignment.
U.S. Pat. No. 4,261,644 involves the use of memory metals for mechanically splicing with application of heat.
U.S. Pat. No. 4,435,03B is directed to deformable material involving three integrally formed elongated members that are squeezed together to align optical fibers.
U.S. Pat. No. 4,597,632 is directed to temperature sensitive releasable optical connector which utilizes a shape memory effect metal to align and clamp ferrules.
U.S. Pat. No. 4,647,150 illustrates an arched alignment of optical fibers utilizing an optical adhesive as well as an innertube for butt-to-butt splicing.
U.S. Pat. No. 4,725,117 describes a complex optical fiber connection utilizing a heat-recoverable tube which is constructed of a memory material such as elastic or plastic memory metals, as well as an outer metal contact body. The basic idea of shrinking a memory plastic radially inward to achieve optical fiber alignment is taught in this patent.
U.S. Pat. No. 4,743,084 involves improvement in the use of deformable plastics or the use of shape memory materials as an integral part of a more complex mechanic structure.
U.S. Pat. No. 4,750,803 describes a connector which includes exit port means to allow air to escape during splicing.
In addition to the above, there were suggested many splicing methods using heat-shrinkable polymers (called also memory polymers, heat-recoverable polymers, etc.) to help align optical fibers. These polymers (described e.g. in U.S. Pat. Nos. 2,027,962; 3,086,242; 3,359,193; 3,370,112; 3,597,372 and 3,616,363) are either thermoplasts or post-crosslinked thermoplasts containing a crystalline polymer phase and/or amorphous polymer phase with relatively low glass-transition temperature due to either nature of the polymer or due to plastification effect. Such heat-shrinkable polymer can be forced into one shape and frozen in it; and shrunk by application of heat approximately into the original shape. Because such heat-shrinkable polymers consist of several polymer phases and/or a multitude of separate polymer chains, they do not have a precise shape which could be called "inherent" and they can return only approximately into a predetermined shape. In addition to that, the highly crystalline polymers must be heated above the melting point of their crystalline phase; the re-crystallization of the polymer causes significant volume contraction which is detrimental to the alignment. Because of that the heat-shrinkable component in itself cannot form a splicer with a low insertion loss. Such splicers require a combination of highly symmetric tubular shape, coupling gels or adhesives and elaborate support structures, which in turn cause a high cost of the device and of its installation. Typical of the patents which show the unique methods of splicing are the following: Great Britain Patent No. 1,588,227 describes a splicing method using heat-shrinkable crystalline thermoplastic sleeve to achieve fiber connection.
Notwithstanding the above prior art references, it should be noted that the present invention has not been anticipated or rendered obvious because the use of a unistructural memory polymer is neither disclosed nor suggested as a complete and simple but advanced structure in and of itself. Further, the unique steps of preparing the memory polymer utilized in the present invention splicer is also lacking in the prior art.